Converters for converting analog signals to digital signals (and vice versa) are found in a wide variety of devices, including compact disc (CD) players, digital video disc (DVD) players, signal processors, and various other systems that communicate signals. In general, the accuracy and quality of the signal conversion process increases with increasing sampling rate provided that the noise introduced by the digitization process (i.e., sampling and quantization) is properly taken into consideration.
Multi-stage noise shaping (MASH) converters may be used to separate and remove noise, particularly for applications in which oversampling is used, such as in certain pulse-width-modulation (PWM) converters. The term oversampling refers to the use of sampling frequencies that exceed a frequency dictated by the Nyquist theorem in order to boost signal-to-noise ratio and reduce quantization noise. Unfortunately, such conventional converter devices remain sensitive to noise introduced by jitter in the sampling clock signal.